// poll.h
// MacOS X does not implement poll().  Therefore, this replacement
// is required.  It uses select().

#ifndef _FAKE_POLL_H
#define _FAKE_POLL_H

#include <sys/errno.h>
#include <string.h>
#include <limits.h>
#undef FD_SETSIZE
#define FD_SETSIZE OPEN_MAX
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdlib.h>

typedef struct pollfd {
    int fd;                         /* file desc to poll */
    short events;                   /* events of interest on fd */
    short revents;                  /* events that occurred on fd */
} pollfd_t;


// poll flags
#define POLLIN  0x0001
#define POLLOUT 0x0004
#define POLLERR 0x0008

// synonyms
#define POLLNORM POLLIN
#define POLLPRI POLLIN
#define POLLRDNORM POLLIN
#define POLLRDBAND POLLIN
#define POLLWRNORM POLLOUT
#define POLLWRBAND POLLOUT

// ignored
#define POLLHUP 0x0010
#define POLLNVAL 0x0020

inline int poll(struct pollfd *pollSet, int pollCount, int pollTimeout)
{
	struct timeval		tv;
	struct timeval		*tvp;
	fd_set			readFDs, writeFDs, exceptFDs;
	fd_set			*readp, *writep, *exceptp;
	struct pollfd		*pollEnd, *p;
	int				selected;
	int				result;
	int				maxFD;

	if ( !pollSet )
	{
		pollEnd = NULL;
		readp = NULL;
		writep = NULL;
		exceptp = NULL;
		maxFD = 0;
	}
	else
	{
		pollEnd = pollSet + pollCount;
		readp = &readFDs;
		writep = &writeFDs;
		exceptp = &exceptFDs;

		FD_ZERO(readp);
		FD_ZERO(writep);
		FD_ZERO(exceptp);
        
		// Find the biggest fd in the poll set
		maxFD = 0;
		for (p = pollSet; p < pollEnd; p++)
		{
			if (p->fd > maxFD)
				maxFD = p->fd;
		}

		if (maxFD >= FD_SETSIZE)
		{
			// At least one fd is too big
			errno = EINVAL;
			return -1;
		}
        
		// Transcribe flags from the poll set to the fd sets
		for (p = pollSet; p < pollEnd; p++)
		{
			if (p->fd < 0)
			{
				// Negative fd checks nothing and always reports zero
			}
			else
			{
				if (p->events & POLLIN)
					FD_SET(p->fd, readp);
				if (p->events & POLLOUT)
					FD_SET(p->fd, writep);
				if (p->events != 0)
					FD_SET(p->fd, exceptp);
				// POLLERR is never set coming in; poll() always reports errors
				// But don't report if we're not listening to anything at all.
			}
		}
	}
        
	// poll timeout is in milliseconds. Convert to struct timeval.
	// poll timeout == -1 : wait forever : select timeout of NULL
	// poll timeout == 0  : return immediately : select timeout of zero
	if (pollTimeout >= 0)
	{
		tv.tv_sec = pollTimeout / 1000;
		tv.tv_usec = (pollTimeout % 1000) * 1000;
		tvp = &tv;
	}
	else
	{
		tvp = NULL;
	}

	selected = select(maxFD+1, readp, writep, exceptp, tvp);

	if (selected < 0)
	{
		// Error during select
		result = -1;
	} 
	else if (selected > 0)
	{
		// Select found something
		// Transcribe result from fd sets to poll set.
		// Also count the number of selected fds. poll returns the 
		// number of ready fds; select returns the number of bits set.
		int polled = 0;
		for (p = pollSet; p < pollEnd; p++)
		{
			p->revents = 0;
			if (p->fd < 0) {
				// Negative fd always reports zero
			}
			else
			{
				if ( (p->events & POLLIN) && FD_ISSET(p->fd, readp) )
					p->revents |= POLLIN;
				if ( (p->events & POLLOUT) && FD_ISSET(p->fd, writep) )
					p->revents |= POLLOUT;
				if ( (p->events != 0) && FD_ISSET(p->fd, exceptp) )
					p->revents |= POLLERR;
				
				if (p->revents)
					polled++;
			}
		}
		result = polled;
	}
	else
	{
		// selected == 0, select timed out before anything happened
		// Clear all result bits and return zero.
		for (p = pollSet; p < pollEnd; p++)
			p->revents = 0;
			
		result = 0;
	}

	return result;
}


#undef FD_SETSIZE

#endif
